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Biomass Basics: Renewable Energy and Chemicals Dennis J. Miller Department of Chemical Engineering and Materials Science Michigan State University East Lansing, Michigan 48824 (517) 353-3928 millerd@egr.msu.edu. Benefits of the Chemical Industry Tell Our Students About It!!.
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Biomass Basics: Renewable Energy and Chemicals Dennis J. Miller Department of Chemical Engineering and Materials Science Michigan State University East Lansing, Michigan 48824 (517) 353-3928 millerd@egr.msu.edu
Benefits of the Chemical IndustryTell Our Students About It!!
The Emerging Paradigm: Sustainability and Green Chemistry "Sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” The Brundtland Commission Report, The United Nations, 1987. • Environmentally Sustainable • Economically Sustainable • Socially Sustainable
Petroleum www.bp.com
Energy Consumption Concepts(A great web site: www.bp.com) • Material and Energy Balances • How much fossil energy in MJ (oil, coal, gas) does the world use annually? • How much oil does the U.S. use annually? (A: about 1.5 cubic miles) • How many watts per person does that equate to in the U.S.?
Corn: The Near-term Biofuels Feedstock 2005 Statistics • Production: 11.8 billion Bushels • Acres planted: 80.9 million acres • Average yield: 160 bushels/acre (vs. 137 bu/a in 2000!) The corn plant • 3.8 tons corn stover / acre (lignocellulosic) • 3.8 tons corn grain / acre Societal/Global perspective questions: How much of our fuel needs can corn provide? What are the costs associated with using corn for fuel? How does politics enter into corn ethanol?
Corn to ethanol energetics C6H12O6 = 2 C2H5OH + 2 CO2 glucose ethanol carbon dioxide 1.0 kg 0.51 kg 0.49 kg 17 MJ 15.8 MJ 0 MJ Theoretical yield 2.7 gal/bu EtOH yield (grain only): 450 gal/acre EtOH yield w/ 50% stover: 670 gal/acre • Ethanol energy content 80,000 Btu/gal • Gasoline energy content 130,000 Btu/gal
Ethanol fuel supply • U.S. gasoline consumption (2006): 150 billion gal • U.S. fuel ethanol consumption (2006): 6 billion gal • 4% of total gasoline demand • Blended 10% with gasoline (40% of U.S. gasoline contains ethanol) • 14 million of 80 million acres of corn harvested Ethanol energy exercises • How much corn would be required to provide E10 for the entire U.S.? A: About ~5 billion bushels (40% of 2006 U.S. crop) • What land mass would be required to replace all U.S. gasoline with ethanol? A: 200 billion gal EtOH equates to 75 billion bushels corn / yr or 300+ million acres (22% of U.S. landmass)!
Cellulosic Biomass – long-term renewable biofuel feedstock Composition (wt%) Wood Switchgrass Cellulose 55 55 Hemicellulose 20 30 Lignin 25 15 Yield (ton/acre) 3 - 8 3 - 10 Ethanol yield (gal/ton) 90 - 100 90 - 100 Challenges • Switchgrass is low-density compared to corn, more costly to collect and transport. • Cellulose difficult to hydrolyze (structural polymer); starch is amorphous and easy to hydrolyze. • Can burn lignin to provide energy for plant operation
Senior Design Problem: Bioenergy plantation design • Fundamental concept: there exists an optimum biorefinery capacity (M) for biofuel production. (Tradeoff between capital cost (~M0.6) and cost of transporting biomass (~M1.5)). • Process energy provided by lignin combustion • Can choose parameters arbitrarily or use standard values (NREL website). • Possibilities for open-ended design, multiple smaller “feeder” process units in remote locations.
Biodiesel from plant oils • Plant oils include soy, rapeseed, canola, etc.. • Waste cooking oils are minor potential source, are inexpensive, • but contain water and free fatty acids that must be cleaned up. • Other sources include algae, sewage, etc.. • Reversible reaction system • Typical methanol:oil feed ratio of 6:1 gives two product phases, • >98% methyl ester yield
Current biodiesel production(Batch production, labor and energy intensive) Biodiesel Product (100 kg) (30 gal) purification Plant oil (100 kg) (30 gal) Methanol (22 kg) (6:1 ratio) Neutralize purify 60oC, 2 hr Glycerol byproduct (10.4 kg) (0.7 lb/gallon) Glycerol + NaOCH3 NaOCH3 (0.5 kg)
Biodiesel in the classroom Material and energy balances: a) Calculate stoichiometric reaction masses, byproduct glycerine yields b) Calculate biodiesel energy density relative to diesel fuel c) Optimizing energy yields from land - Which fuel type gives higher energy yield per acre, biodiesel or ethanol? Canola: 1000 kg/acre*0.44 kg oil/kg canola*39 mJ/kg = 17160 MJ/acre Ethanol: 160 bu/acre*2.7 gal/bu*3 kg/bu*27 MJ/kg = 35000 MJ/acre Reaction engineering: Make biodiesel as classroom demo (cooking oil + methanol + sodium hydroxide/methoxide) Good example of homogeneous catalysis (can see color change upon addition of sodium hydroxide in methanol)
Chemical Building Blocks from Biomass Carbon numberBiomass BlocksPetroleum Blocks C1 methanol, CO methane C2 acetic acid, ethanol ethylene C3 lactic acid, acetone, propylene propionic acid, glycerol C4 succinic acid, n-butanol isobutylene 3-hydroxybutyrate butadiene C5 xylose, glutamic acid 3-hydroxyvalerate C6 glucose, lysine benzene C7, C8 toluene xylene
Chemicals from Carbohydrates BIOMASS (CORN, WOOD..) STARCH CELLULOSE Industrial starches, cellulose derivatives CORN GLUCOSE Syrups, sweeteners Fermentation Chemical conversion O2 H2 Organic acids Others Polymers Gluconic acid Sorbitol Ethanol Lactic acid Succinic acid Citric acid Acetic acid Propionic acid Itaconic acid Lysine D,L-Methionine Other amino acids Aromatics 1,3-propanediol 2,3-butanediol ABE Starch copolymers Xanthan gum Alginates Hydroxyalkanoate PG, EG Glycerol Sorbitan Ascorbic acid
Lactic Acid Fermentation: C6H12O6 2 C3H6O3 (glucose) (lactic acid) - Yields exceed 0.95 lb/lb glucose - Product concentrations > 90 g/L - Production rates > 3 g / L· hr - Ca(OH)2 to neutralize, acidulation w/ H2SO4 (CaSO4 waste) Production cost: < $0.25 / lb Production capacity: 350 MM lb/yr (Cargill) 100 MM lb/yr (all others)
Equilibrium Lactate Ester Reactions - Lactic acid oligomerization reactions characterized by Ke = 0.23 Equilibrium oligomer distribution
Ethanol + Water Water Lactic Acid Ethyl Lactate Ethanol Ethyl Lactate (+ oligomers) Lactate esters via reactive distillation Lactic Acid + Ethanol = Ethyl lactate + Water
Feed Stream 1 Flow 21.87 kmol/hr 25C Wt % LA 58.0 Water 14.0 L2 Acid 22.0 L3 Acid 8.0 Feed Stream 2 Flow 54.0 kmol/hr 85C 1.16 atm Wt % EtOH 100.0 Reactive distillation for lactate ester production Stream 3 Flow 65.98 kmol/hr Wt % EtOH 82.93 EtLA 0.13 Water 16.94 FEED (88% LA feed) LA : 9.519 kmol/hr L2 Acid : 2.005 kmol/hr L3 Acid : 0.505 kmol/hr Water : 9.847 kmol/hr EtOH : 54.000 kmol/hr 7 10 Stream 4 Flow 9.90 kmol/hr 30 Wt % LA 0.00 EtOH 0.30 EtLA 72.64 Water 0.13 L2ES 19.44 L3ES 6.11 L2 Acid 0.66 L3Acid 0.63 35 # Stages 35 Reflux ratio 0.1 Lactic acid conversion (%) >99
Chemicals from Renewables • Material balances/reaction engineering: Determine theoretical yields - renewables generally undergo weight loss in conversion, whereas petroleum generally undergoes weight gain in conversion. • Separations: schemes for purifying low volatility organic/renewable products (evaporation, reactive distillation, chromatography, other novel separations) • Thermodynamics: Many biobased reactions are reversible, involve nonideal solutions, physical properties estimation required
Summary • Renewable fuels and chemicals can be incorporated across the core ChE curriculum • Energy and mass balance calculations • Thermodynamics: physical properties, phase equilibria, reaction equilibria • Reaction engineering: kinetics, reactor design, catalysis • Separations: design separations schemes for non-volatile, thermally fragile compounds • Process design: core chemical engineering principles and unit operations are key to designing biorefineries
GREEN CHEMISTRY DEFINITION Green Chemistry is the utilisation of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture and application of chemical products*. GREEN CHEMISTRY IS ABOUT (12 principles) • Waste Minimisation at Source • Use of Catalysts in place of Reagents • Using Non-Toxic Reagents • Use of Renewable Resources • Improved Atom Efficiency • Use of Solvent Free or Recyclable Environmentally Benign Solvent systems
Traditional Synthesis of Ibuprofen O O CHCO2C2H5 ClCH2CO2C 2H5 (CH3CO)2O NaOC2H5 AlCl3 I¯Bu I¯Bu CH NOH CHO H2NOH H+ H20 I¯Bu I¯Bu CO2H 60% Waste N C Ibuprofen I¯Bu (BASF and Celanese Corporation)
O H2 catalyst Green Chemistry Alternative Synthesis of IbuprofenPGCC Winner 1997 (CH3CO)2O + CH3COOH HF CO2H OH CO, Pd 1% Waste Ibuprofen (BASF and Celanese Corporation)
Green chemistry in the curriculum • Material and Energy Balances • Define and implement atom economy and waste generation into stoichiometry problems • Yield calculations for multiple step syntheses • Reaction Engineering and Design courses • Carry out reactor design for green process and compare with traditional process • Resource: ACS Green Chemistry Institute